Upgrade one or many distribution lists to Office 365 Groups in Outlook

In the Exchange Admin Center, go to Recipients > Groups.You'll see a notice indicating you have distribution lists (also called distribution groups ) that are eligible to be upgraded to Office 365 groups.

Select one or more distribution lists (also called a distribution group ) from the groups page.

Choose the upgrade icon.

On the information dialog, choose Yes to confirm the upgrade. The process begins immediately. Depending on the size and number of DLs you're upgrading, the process can take minutes or hours.If the distribution list can't be upgraded, a dialog appears saying so. See Which distribution lists can be upgraded?.

If you're upgrading multiple distribution lists, use the drop down to filter which distribution lists have been upgraded. If the list isn't complete, wait a while longer and then choose Refresh to see what's been successfully upgraded.There's no notice that tells you when the upgrade process has completed for all DLs you selected. You can figure this out by looking to see what's listed under Available for upgrade or Upgraded DLs.

If you're getting the groups digest emails you may notice at the bottom that it will sometimes offer to let you upgrade any eligible distribution lists that you're the owner of. See Have a group conversation in Outlook for more information about digest emails.

What to do if the upgrade doesn't work

Distribution lists that fail to upgrade remain unchanged.

If one or more eligible distribution lists fail to be upgraded, open a Support ticket. The issue will need to be escalated to the Groups Engineering team for them to figure out the problem.

It's possible that the distribution list didn't get upgraded because of a service outage, but pretty unlikely. If you want, wait a while and then try to upgrade the DL again.

How to use PowerShell to upgrade several distribution lists at the same time

If you're experienced at using PowerShell, you might want to go this route instead of using the UI. We have a set of cmdlets that will help you upgrade distribution lists. See below.

Upgrade a single DL

To upgrade a single DL run the following command:

Upgrade-DistributionGroup -DlIdentities \<Dl SMTP address\>

For example, if you want to upgrade a DLs with SMTP address dl1@contoso.com, run the following command:

Upgrade-DistributionGroup -DlIdentities dl1@contoso.com

Note

You can also upgrade a single distribution list to an Office 365 group using the New-UnifiedGroup PowerShell cmdlet

How do I check which DLs are eligible for upgrade?

If you want to check which DLs are eligible for upgrade just run the following command:

Get-EligibleDistributionGroupForMigration

Who can run the upgrade scripts?

People with Office 365 global admin or Exchange admin rights.

Why is the contact card still showing a distribution list? What should I do to prevent a upgraded distribution list from showing up in my auto suggest list?

For Outlook: When someone tries to send an email in Outlook by typing the Office 365 group name after migration, the recipient will be resolved as the distribution list instead of the Office 365 group. The contact card of the recipient will be the distribution lists contact card. This is because of the recipient cache or nick name cache in Outlook. The email will be sent successfully to the Office 365 group, but might cause confusion to the sender.You can perform the steps in this topic, Information about the Outlook AutoComplete list to reset the cache, which will fix this issue.

Do new group members get a welcome email in their inbox?

No. The setting to enable welcome messages is set to false by default. This setting affects both existing and new group members who may join after the migration is complete. If the group owner later allows guest users, guest users won't receive a welcome email in their inbox. Guest members can continue working with the group.

What if one or some of the DLs are not upgraded?

There are some cases in which though DL is eligible but could not be upgraded. The DL does not get upgraded and remains as a DL.

Where admin has applied Group Email Address Policy for the groups in an organization and they try to upgrade DLs which doesn't fulfill the criteria, the DL does not get upgraded

DLs with MemberJoinRestriction or MemberDepartRestriction set to Closed, could not be upgraded

What happens to the DL if the upgrade from EAC fails?

The upgrade will happen only when the call is submitted to the server. If the upgrade fails, your DLs will be intact. They will work like they used to.